为了定量研究雷暴过程中电晕空间电荷对特高压直流输电线路后续流注放电起始的影响,基于带通量限制器的2阶有限体积方法和Kaptzov假设,建立雷暴过程中特高压直流输电线路电晕空间电荷分布的数值仿真模型。通过开展动态电场下水平导线电晕放电电流的实测与仿真对比研究,验证了模型的准确性。计算分析典型±1100kV特高压直流输电线路雷暴过程中导地线电晕电流时域波形和电晕空间电荷分布特征。得出下行先导趋近过程会显著增加导、地线表面附近约0.5m范围内正离子密度,并使导、地线电晕电流最大值较雷云电场作用时增加6～7个数量级。随着地线表面附近正离子密度增加,电场最大值从地线表面向导线附近空间移动,而导致后续流注产生。所作研究工作可为后续研究电晕空间电荷对特高压直流线路雷电绕击特性的影响奠定基础。

Construction of ±1100kV UHVDC transmission channels from West to East in China is conducive to promote large scale optimal allocation of energy sources. In UHVDC transmission systems, main DC equipment development, project implementation, reliability level and power loss caused by converter outage are deeply impacted by main connection line of converter and main circuit parameters. This is also the most important step of project system research. Firstly, evaluation method of converter connection line of UHVDC projects are proposed in this paper. Secondly, according to previous project construction, equipment design and manufacturing experiences, three converter connection schemes are proposed and main circuit parameters are analyzed respectively based on each connection scheme. Finally, a proposed assessment method of converter main connection line is used to determine a reasonable and effective main connection topology for Changji-Guquan ±1100kV UHVDC project.

受雷云电场和直流工作电压的叠加作用,导地线因电晕放电产生大量正、负离子积聚在线路附近形成空间电荷层。为研究电晕空间电荷对特高压直流线路雷电绕击性能的影响,建立了雷云电场作用下线路电晕空间电荷分布的数值计算模型,并耦合雷电先导发展模型,计算获得了典型±1100 kV特高压直流输电线路的地线雷电上行先导放电特性和雷电击距,定量分析了电晕空间电荷对特高压直流输电线路地线雷电上行先导起始时刻、放电电流和长度的影响。通过计算电晕空间电荷作用下地线的雷电击距和暴露弧,得出在平原地区仍可通过采用负保护角配置,有效降低线路的雷电绕击概率,未来需进一步研究山区地形下电晕空间电荷对特高压直流线路雷电绕击性能的影响规律。

Distance between two lines in important UHV transmission channel is usually short,and lightning shielding characteristics of a ±1100kV line with an adjacent line in parallel is different from those of single ±1100kV line.At the same time,UHV transmission distance is far long,passing complex terrains,and polarity arrangement of ±1100kV line also has important influence,affecting lightning shielding effect.Based on basic principle of electrogeometric model (EGM) and considering lightning shielding effect between adjacent parallel lines at different slope angles,an improved EGM is established in this paper.The slope angle,distance between adjacent lines,and polarity arrangement of ±1100kV line,all having impact on lightning shielding characteristics of ±1100kV line,are fully investigated,and shielding failure rate (SFR) of each conductor under influence of different factors is calculated.This paper uses lightning shielding factor (Sf) to quantitatively describe lightning shielding effect of adjacent lines.Results show that under the same conditions,the shielding failure rate of transmission line increases significantly with increase of slope angle;the closer the adjacent lines are,the stronger lightning shielding effect is.When the slope angle is bigger than 15°,comprehensive analysis recommends that ±1100kV negative polarity conductor should be arranged on downhill side,close to the adjacent line,making the two lines as close as possible,then the shielding failure rate of±1100kV line would decrease significantly.This study has guiding significance for transmission line lightning protection design of important UHV transmission channel.

为了研究电晕空间电荷对特高压直流输电线路雷电绕击特性的影响机制,基于带通量限制器的二阶有限体积方法,建立了雷云电场下特高压直流输电线路电晕空间电荷分布的数值仿真模型,通过与实验对比,验证了模型的合理性.计算获得典型±1 100 kV特高压直流输电线路电晕起始过程、电晕电流波形和空间电荷分布特征,得出正空间电荷边界在垂直地面方向的平均运动速度为4.05 m/s.考虑到电晕空间电荷引起的电位畸变对雷电上行先导存在屏蔽作用,通过分析不同时刻电位畸变量分布,得出雷云电场下电位畸变集中分布于地线上方,相较于仅存在直流工作电压情况,电位畸变量最大值增加了约20倍.由此推断,受电晕空间电荷影响平原地区±1 100kV线路地线产生的上行先导更易沿水平方向发展.该工作为后续研究电晕空间电荷对特高压直流线路雷电绕击特性的影响奠定了基础.

For UHVDC project,corona discharge may start if the maximum electric field of electrode surface reaches corona electric field.The shape and structure of different equipment are having large difference for ±1100kV UHVDC project DC yard,and the zero potential wall and roof are presented and increase the surface electrical field,thus the all domain 3D electric field simulation of indoor DC yard is necessary for repeated optimization of electrode shape.In this paper,the electric field simulation study and test were carried out to state the permitted electrical filed of electrode with different diameter.By 3D simulation and continuously optimizing the electrode shape of the critical equipment in 1100kV indoor DC yard,the maximum electric field of electrode surface meets the permitted value requirement finally.

The wide application of communication optical cable can significantly improve the anti-interference ability of the communication system, and the DC transmission project has the technical conditions to simplify the design of direct current filter (DCF) and improve the interference limit value. ±1100kV UHVDC project DCF is huge and difficult to develop, which will seriously affect the technical scheme of the indoor DC Yard, and it is necessary to simplify the design. Simplified DCF design principle and step were proposed. The basic form of simplified filter was determined with the minimum resonant branch which is necessary. Based on ±1100kV project,to limit crest value of continuous operating voltage (CCOV) of the DC circuit, the main capacitor, parallel resonant frequency, filter resistance value, filter resistance connection form were optimized. The simplified DC filter technique program was put forward for the world's first ±1100kV UHVD project, which reduces the main capacitance value of the DC filter, reduces the volume and occupation of the filter tower, reduces the difficulty of the equipment development, and saves the investment of the project.

同走廊两回±800 kV直流线路不久将在中国出现,需要对该种线路的地面合成电场进行研究,为工程设计和环境保护提供技术依据。对同走廊两回直流线路极导线按不同方式布置时的地面合成电场进行模拟试验,获得了其横向分布规律。给出一种同走廊两回直流线路地面合成电场的计算方法,该方法考虑了影响此种线路地面合成电场的多种重要因素,模拟试验验证了所提计算方法的有效性。采用该方法分析了同走廊两回±800 kV直流线路地面合成电场的分布特点。结果表明:不同的极导线布置方案不会显著影响同走廊两回直流线路地面最大合成电场的大小,但会影响其分布位置;同走廊两回直流线路地面最大合成电场的绝对值与单回直流线路运行时差别不大;两回±800 kV直流线路同走廊临近架设与相距较远距离架设相比,能大幅减少线路走廊宽度和工程拆迁费用。

The application of large cross-section conductor can effectively reduce the current density and realize the strategy of energy saving & consumption reduction. This paper introduces the large cross-section conductor (900 mm2) applied in the ±800 kV Jinping-Sunan UHV DC project, and focuses on the analysis of factors concerning the conductor's engineering application. The factors include structure design and manufacturing of conductor, fittings, engineering technology, etc. The conclusion is finally drawn: it is feasible and necessary to design a four-layer aluminum strand for conductors with the dimension of 900 mm2, by which the productivity has the expanding potential;there are no obstacles to the design and manufacturing of fittings;the releasing scheme should be further optimized;the existing traction and stretching machines can be used and the pulley and card conductor should be developed. It also indicates that large cross-section conductor (900 mm2) is expected to have a broad application.

The aluminum conductor with reinforced core of composite material is a brand new conductor for overhead lines in which the steel core is substituted by the core of composte material.This kind of conductor adequately brings the strong point of organic material into play and possesses advantages such as light in weight,high intensity,thermostable,corrosion resistant,low loss and low sag.In this paper the technical characterstic,performance index and application situation of concerned products of composite core conductors developed in Japan and United States are presented,the technical feasibility,economy and prospect of application of conductor with reinforced core of composite material are assessed.